[1] McGill Univ, Dept Family Med, Montreal, PQ H3A 2T5, Canada
[2] UCL, Res Dept Primary Care & Populat Hlth, London, England
[3] Barts & London Queen Marys Sch Med & Dent, Ctr Hlth Sci, London, England
[4] Univ S Australia, Sch Publ Hlth, Adelaide, SA 5001, Australia
[5] Univ Western Ontario, Schulich Sch Med & Dent, London, ON, Canada
[6] Community Campus Partnerships Hlth, Seattle, WA USA
[7] Univ Calif San Francisco, San Francisco, CA 94143 USA